Non-hazardous oxidative neutralization of aldehydes

ABSTRACT

Methods, compositions, and devices for alleviating the problems of toxic discharge of aldehydes present in waste streams are disclosed. The methods relate to forming neutralized aldehydes by treating aldehydes with oxidizing agents. The oxidizing agents offer a simple, effective, fast and inexpensive solution for treatment of toxic aldehydes prior to disposal into the environment.

RELATED APPLICATIONS

[0001] This patent application is related to concurrently filed andcommonly assigned patent application U.S. Ser. No. ______, filed Jun.29, 2001 entitled “NON-HAZARDOUS BASIC NEUTRALIZATION OF ALDEHYDES”(Attorney Doc. No. ASP-0028), the disclosure of which is incorporated byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to neutralization of aldehydes for thepurpose of complying with waste disposal requirements established byfederal and state environmental protection agencies, in particular, withforming non-reversible neutralized aldehydes which are non-hazardous anddo not revert back to toxic aldehydes.

[0004] 2. Description of Related Art

[0005] Waste disposal of aldehydes has become increasingly moredifficult over the years. Treatment of wastes containing a certainamount of aldehyde prior to placement of the waste into the environmentis required by law. The extent of such treatment may vary depending uponthe location of where the waste is generated and the stringency of theenvironmental standards in that area. For example, waste containingaldehyde may be classified as a hazardous waste in California under 22CAL. CODE REGS., TIT. 22, §66696. Formaldehyde also may be considered ahazardous waste on the federal level under 40 C.F.R. §261.33(e) if it isa commercial chemical product (e.g., pure technical grade formaldehydeor formaldehyde is the sole active ingredient of the product that is tobe disposed). Every state has an environmental regulation that is atleast as stringent as this formaldehyde standard. State regulations alsomay be more stringent than this standard.

[0006] Additionally, facilities that discharge waste water to PubliclyOwned Treatment Works (“POTW”) or directly into navigable waters may berequired to meet standards that are established by a government agency.The standard may vary for each facility depending upon the quality ofthe receiving water and the concentration of aldehyde found in the wastewater that is discharged into the environment by industry in that area.

[0007] Waste containing aldehyde may be generated by a variety ofprocesses. For example, aldehydes such as glutaraldehyde ando-phthalaldehyde (“OPA”) are used in disinfecting medical devices orinstruments. Waste containing aldehydes also may be generated bypainting operations, stripping operations related to floors, or othermanufacturing operations.

[0008] Typically, ammonia and sodium bisulfite (“SBS”) are used to treatmany aldehydes. These compounds, however, have not proven to beeffective at neutralizing OPA in accordance with environmentalregulations.

[0009] A waste is classified as a hazardous waste in California if thewaste being examined “has an acute aquatic 96-hour LC₅₀ less than 500milligrams per liter (mg/L) when measured in soft water (total hardness40 to 48 milligrams per liter of calcium carbonate) with fathead minnows. . . . ” 22 CAL. CODE REGS., TIT. 22, §66696. LC₅₀ represents theconcentration of a waste that is necessary to kill 50% of a particularanimal exposed to a waste.

[0010] Note that a nonhazardous waste is generally considered by federaland state environmental agencies as a waste that does not satisfy thecriteria set forth in defining a hazardous waste. Therefore, wastesgenerated in California that have a LC₅₀>500 mg/L are nonhazardouswastes and wastes having LC₅₀<500 mg/L are classified as hazardous. SBS,for example, in combination with OPA, produces a product that isgenerally considered hazardous under California environmental law asshown in Table 1 by LC₅₀ being consistently below 500 mg/L. For thisstudy, CIDEX® OPA (commercially available from Advanced SterilizationProducts®, a Johnson & Johnson Company of Irvine, Calif.) was used tosupply the OPA. TABLE 1 Neutralization Of OPA Using SBS OPA Content LC₅₀Sample Type (%) (mg/L) Comments Fresh CIDEX ® OPA at 0.3% 0.301% 31.1mg/L 1 OPA Fresh CIDEX ® OPA at 0.15% 0.158% 50.4 mg/L 2 OPA ReuseCIDEX ® OPA at 0.3% 0.295% 31.1 mg/L 3 OPA SBS/OPA = 4:1 N/A 68.3 mg/L 4SBS/OPA = 2:1 N/A 46.3 mg/L 5

[0011] In addition to lacking the ability to effectively neutralize OPA,ammonia and SBS are problematic since they may be harmful to theenvironment.

[0012]FIG. 1 shows that when OPA is combined with SBS at the molar ratioof SBS/OPA=4:0 for 30 minutes, OPA has been neutralized since the OPAconcentration is nondetectable in a high performance liquidchromatography (HPLC) analysis method, which has detection limit for OPAat 10 ppm. However, the end product is still classified as a hazardouswaste as shown in Table 1. Therefore, even though the aldehyde isneutralized completely by a neutralizer, the end product may still be ahazardous waste.

[0013] The purpose of this invention is to invent an effective,non-hazardous, convenient and inexpensive neutralizer forglutaraldehyde, o-phthalaldehyde (OPA) and/or other aldehydes.Glutaraldehyde and o-phthalaldehyde are the main chemicals used inindustry and hospital for high-level disinfection. The glutaraldehyde oro-phthalaldehyde needs to be neutralized after use before disposal,however, at this point, there are only very limited neutralizationmethods available. Commonly assigned patent application U.S. Ser. No.09/321,964, entitled “ALDEHYDE NEUTRALIZER” suggests using amino acidssuch as glycine as neutralizers. While use of glycine offers aninexpensive, fast and non-hazardous solution to aldehyde neutralization,there are, however, some problems with the amino acid neutralizerapproach. One problem is that Schiff's base solutions formed betweeno-phthalaldehyde and glycine is black. In Japan, the general feeling isthat they do not like black color; therefore, hospitals send their usedsolution to the waste treatment companies for disposal, which isexpensive. Another approach to the problem of aldehyde neutralization isoffered by commonly assigned and co-pending patent application U.S. Ser.No. 09/747,230 entitled “REDUCTIVE AMINATION FOR ALDEHYDENEUTRALIZATION” which teaches the reaction of aldehydes with amino acidneutralizers followed by reduction of the resulting imines to form aminoacids as final environmentally friendly products. This method is bestcarried out on solid supports and the solid waste is disposed afterapplication. In another approach, commonly assigned and copending patentapplication U.S. Ser. No. 09/746,344, entitled, “DEVICE AND METHOD OFUSE FOR ALDEHYDE REMOVAL”, discloses using polymeric amines asscavengers to remove aldehydes from waste solutions. Although thismethod removes both glutaraldehyde and o-phthalaldehyde from the useddisinfectant solution, the solid waste still must be handled separately.

[0014] Thus different approaches to the challenge of aldehydeneutralization are still needed for various situations. This inventionis intended to offer another approach relating to neutralization ofaldehydes as hereinafter described.

SUMMARY OF THE INVENTION

[0015] One embodiment of the invention relates to a method for making aneutralized aldehyde of lessened toxicity comprising the steps of:

[0016] a) providing an aldehyde; and

[0017] b) contacting the aldehyde with an effective amount of anoxidizing agent to render the treated aldehyde as neutralized and lesstoxic compared with the untreated aldehyde.

[0018] Another embodiment of the invention relates to a system forneutralizing aldehydes and making the aldehydes less toxic comprising:

[0019] a) a container;

[0020] b) a source of aldehyde selected from the group consisting ofo-phthalaldehyde, glutaraldehyde, formaldehyde and mixtures thereofdirected to the container; and

[0021] c) a source of oxidizing agent directed to the container to yieldtreated aldehydes of lower toxicity than the untreated aldehydes.

[0022] A major advantage of this invention is that it is a simple, fast,inexpensive, and non-hazardous method to neutralize aldehydesterilization solutions. When hydrogen peroxide is used as the oxidant,it safely turns to water. The end product of oxidation of aldehydes areeither colorless or lightly colored as opposed to some of the darkcolored products formed by amino acid neutralization of aldehydes asexplained above.

[0023] Additional features, embodiments, and benefits will be evident inview of the FIGURES and detailed description presented below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The features, aspects, and advantages of the invention willbecome more thoroughly apparent from the following detailed description,appended claims, and accompanying drawings in which:

[0025]FIG. 1 shows the ratio of SBS:OPA and the concentration of OPAremaining in solution after 30 minutes from combining the ingredients.

DETAILED DESCRIPTION OF THE INVENTION

[0026] The invention relates to methods and compositions particularlyuseful for the environmentally friendly and non-reversibleneutralization of aldehydes present in waste generated from sterilizingmedical devices (e.g., scalpels, scissors, endoscopes, etc.) orlaboratory equipment (e.g., glassware) that have been exposed tomicroorganisms such as bacteria. As used herein, the term non-reversibleis intended to refer to the substantial prevention of the neutralizedaldehyde (e.g., amino acid treated aldehyde) from reverting back to thestarting or unneutralized aldehyde. Sterilizing includes disinfectingmedical devices.

[0027] The neutralizer comprises oxidants. Suitable oxidants areselected from the group consisting of hydrogen peroxide, benzoylperoxide, peroxyformic acid, peroxyacetic acid, trifluoroperacetic acid,peroxybenzoic acid, ammonium cerium nitrate, nitric acid, ammoniumnitrate, potassium chromate, sodium dichromate, potassium dichromate,chlorine, sodium chlorate, sodium hypochlorite, potassium hypochlorite,calcium hypochlorite, sodium hypobromite, sodium hypoiodite, potassiumhypoiodite, sodium iodate, periodic acid, sodium periodate, potassiumperiodate, manganese dioxide, potassium manganate, potassiumpermanganate, potassium persulfate, magnesium permanganate, rutheniumtetroxide and mixtures thereof.

[0028] When the oxidant is used in solution form, suitable solventscomprise water and alcohol. Suitable alcohols may include methanol,ethanol, isopropanol, n-propanol, and butanol. Water or alcohol may alsocontain acetone, acetonitrile, or tetrahydrofuran (THF).

[0029] Oxidants are an improvement over the typical chemicals such asammonia or sodium bisulfite used to neutralize aldehydes since theoxidants quickly and effectively neutralize aldehydes to a levelprescribed by federal and state environmental agencies. Effectiveamounts of the oxidant to the aldehydes will vary based on the aldehydebeing neutralized and the oxidizer used.

[0030] In the case of glutaraldehyde as the aldehyde and hydrogenperoxide as the oxidizer, nonhazardous neutralization will occur whenthe molar ratio range of glutaraldehyde to hydrogen peroxide istypically at least about 1:1, typically from about 1:1 to 1:100;preferably from 1:4 to 1:50, and most preferably from 1:8 to 1:16. Inthe case of glutaraldehyde and sodium hypochlorite as the oxidizer,nonhazardous neutralization will occur when the molar ratio range ofglutaradehyde to sodium hypochlorite is typically about at least 1:1.5,typically from about 1:1.5 to 1:100; preferably from 1:2 to 1:50, andmost preferably from 1:3 to 1:16.

[0031] In the case of o-phthalaldehyde as the aldehyde and hydrogenperoxide as the oxidizer, nonhazardous neutralization will occur whenthe molar ratio range of o-phthalaldehyde to hydrogen peroxide istypically at least about 1:0.7, typically from about 1:0.7 to 1:100;preferably from 1:1 to 1:10, and most preferably from 1:1.4 to 1:7. Inthe case of o-phthalaldehyde and sodium hypochlorite as the oxidizer,nonhazardous neutralization will occur when the molar ratio range ofo-phthalaldehyde to sodium hypochlorite is typically at least about1:06, typically from about 1:0.6 to 1:50; preferably from 1:0.8 to 1:5,and most preferably from 1:1 to 1:2. In the case of o-phthalaldehyde andpotassium persulfate as the oxidizer, nonhazardous neutralization willoccur when the molar ratio range of o-phthalaldehyde to potassiumpersulfate is typically at least about 1:8, typically from about 1:8 to1:100; preferably from 1:9 to 1:50; and most preferably from 1:10 to1:25.

[0032] To neutralize aldehydes, the oxidizer in solution or in solidform may be added to waste water that is in a tank (e.g., aneutralization tank at a waste water treatment plant), or in a smallcontainer (e.g., a bucket) where aldehydes must be neutralized beforethey are placed into a sewer system that may discharge to a POTW or intonavigable waters. Solids contaminated with aldehydes (e.g., dirt, rags,or gloves, etc.) may be neutralized by directly adding the neutralizerto the solids or by placing the solids into a container with theneutralizer and, optionally, water.

[0033] Thus another embodiment of the invention relates to a system forneutralizing aldehydes and making the aldehydes less toxic comprising:

[0034] a) a container;

[0035] b) a source of aldehyde selected from the group consisting ofo-phthalaldehyde, glutaraldehyde, formaldehyde and mixtures thereofdirected to the container; and

[0036] c) a source of oxidizing agent directed to the container to yieldtreated aldehydes of lower toxicity than the untreated aldehydes.

[0037] Additionally the system may further comprise a source of a pHadjusting material to adjust the pH of the treated aldehyde.

[0038] The source of materials suitable for use in conjunction with thesystems of this invention are the same as disclosed above in thediscussion relating to the methods of this invention. Additionally, thesystem may contain controls on any of the sources added to the containerto achieve the treated aldehyde having a LC₅₀ greater than 500 mg/L orany other desired non-toxicity level.

EXAMPLES

[0039] Unless specified, all the reactions were performed at roomtemperature and concentrations are expressed on a w/v % basis except asnoted and except when reference is made to 0.55% (w/w %) OPA from CIDEX®OPA Solution and 2.4% (w/w %) glutaraldehyde from CIDEX® Glutaraldehydewherein these solution as expressed on a weight to weight basis.

[0040] Two methods were used to evaluate the extent of neutralization.The first method is the thin layer chromatography visualization (“TLCvisualization”) method. In general, the TLC visualization methodcomprises the following steps: (a) spotting a sample of the solution onthe bottom of a TLC plate (usually silica plate), (b) placing the TLCplate in a solvent chamber with the plate side spotted with sample atthe bottom. The solvent (usually mixed solvents) is selected so that allthe components in the sample mixture is developed into isolated spotsafter developing (c) developing (letting the solvent climbing the TLCplate) and letting the mixture being pushed upward and separated intoisolated spots (d) visualization (to show the separated spot visuallywith the aid of displaying agent, or fluorescence etc.). In the case ofthe method used in the following examples, if aldehdye was present,spots (or bands) would display a blue color with pink background upondipping in Schiff's reagent (Fluka 84655, diluted to 10% concentrationwith ethanol).

[0041] The second method used was based on the visual examination ofcolor of the solution (“Color visualization”). Glycine solution (1%) wasused to detect the presence of OPA. The appearance of any green color ordark green or black green is a good indication of the presence of OPA.If only one aldehyde group was present (if the other reacted with anoxidant), other color would display upon adding glycine, such as yellow,yellowish orange or orange or even reddish colors. Although the darknessof the green-flavored color of the Schiff's base formed between glycineand OPA is good indication of OPA level, one have to keep in mind thatthe Schiff's base could be oxidized by many oxidants to cause darkercolor. Caution must be taken where comparison is needed in thesesituations. Although HPLC analysis is an ultimate tool for the analysisof di-aldehyde remaining, we found that the above estimation is quitesufficient for our purpose.

[0042] (A) Neutralization of Glutaraldehyde (Examples 1-8)

Example 1

[0043] To 0.5 mL of 2.4% glutaraldehyde, 0.5 mL of 59% hydrogen peroxidewas added at room temperature. Immediately after mixing, the resultingsolution was tested by: (a) the TLC visualization method using 1%glycine, with the results not showing any green or green to dark colorin a period of 1 hour; and (b) a drop of Schiff's reagent (Fluka) testsolution was added, no positive results (no pink or purple color) wasobserved. Therefore, under the test conditions, the oxidant, hydrogenperoxide, is effective in neutralizing the glutaraldehyde.

Example 2

[0044] Into 6 beakers (50 mL) indicated below as 2-1 through 2-6, 1 mL10% hydrogen peroxide was added, glutaraldehyde (2.4%) of differentvolumes, 24.53, 12.27, 6.13, 3.07, 1.53, 0.77 mL respectively, wereadded to beakers #2-1 through 2-6, respectively. The solutions wereshaken briefly and let stand for 2 hours. Different amounts of waterwere added to the beakers to make them to same volumes (25.53 mL). Thesolutions were spotted onto a TLC silica plate on plastic (Aldrich) anddried in an oven at 75° C. for 3 minutes and developed in anethanol:methylene chloride (1:4) solution. The plates were brieflydipped in Schiff's reagent (Fluka) (diluted to 10% with ethanol) andheated in an oven (75° C.) for 5 minutes to visualize (blue spots withpink background). The oxidant to aldehyde mole ratio and volume ratioare summarized in Table 2. Vial “R” was 2.4% glutaraldehyde used asreference. Results indicated that, under the test conditions, 2 volumesof 10% H₂O₂ is effective to neutralize 3 volumes of 2.4% glutaraldehyde.TABLE 2 Effect of Hydrogen Peroxide (10%) and Glutaraldehyde (2.4%)Mixing Ratio Exp. # 2-1 2-2 2-3 2-4 2-5 2-6 R Vol (10% 1:25 1:12 1:6 1:31:1.5 1:0.77 Ref. H₂O₂):Vol (2.4% Glutaraldehyde) H₂O₂:Glutaralde- 1:2 1:1  2:1 4:1 8:1   16:1    hyde Mole Ratio TLC visualization Spot sizedecreases from No spot exp. 1 to 4 No (All smaller than referenceglutaraldehyde spot) left Some glutaraldehyde left

Example 3

[0045] From Example 2, the solution of 2-2 (hydrogenperoxide:glutaraldehyde volume ratio 1:12 and mole ratio 1:1) was used.After mixing of 10% hydrogen peroxide (1 mL) and 2.4% glutaraldehyde(12.27 mL), 1 mL of the mixed solution was mixed with 0.2 mL IN sodiumhydroxide solution. After standing at room temperature overnight, noglutaraldehyde was left based on the TLC result (same TLC condition).Adding base helped the oxidation.

Example 4

[0046] Same as in Example 3, but 0.2 mL 10% hydrochloric acid was usedinstead of sodium hydroxide. Glutaraldehyde level did not significantlydrop after standing at room temperature overnight as seen from TLCresult. Adding acid did not significantly promote the oxidation.

Example 5

[0047] To 1.0 mL of glutaraldehyde (2.4%) (un-activated), 0.5 mLhousehold bleach (5% NaOCl) was added and the solution gradually turnedyellow.

[0048] The oxidation reaction was followed by TLC visualization at 5minutes and 20 minutes. The solutions were spotted onto a TLC silicaplate on plastic (Aldrich) and was blown with air for 1 minute beforedeveloping in an ethanol:methylene chloride (5:95(V/V)) solution. Theplates were briefly dipped in Schiff's reagent (Fluka) (diluted to 10%with ethanol) and heated in an oven (75° C.) for 5 minutes to visualizeblue spots with a pink background indicating glutaraldehyde was stillpresent. Most of the glutaraldehyde was not oxidized in 5 minutes whilealmost all the glutaraldehyde was oxidized in 20 minutes.

Example 6

[0049] To 6 vials (2 mL) indicated below as 6-1 through 6-6, 100, 200,350 500, 650 and 800 μL bleach (5% sodium hypochlorite) were addedrespectively. Glutaraldehyde (2.4%) of different volumes, 900, 800, 650,500, 350 and 200 μL were added to beakers 6-1 through 6-6, respectively(Table 3). The solutions were shaken briefly and allowed to stand for 20minutes. The solutions were spotted onto TLC silica plate on plastic(Aldrich) and was blown with air for 1 minute before being developed inan ethanol:methylene chloride (5:95(V/V)) solution. The plates weredipped in Schiff's reagent (Fluka) (diluted to 10% with ethanol) brieflyand heated in oven (75° C.) for 5 minutes to visualize blue spots withpink background. Vial “R” was 2.4% glutaraldehyde control. The colors ofsolutions indicate the amount of oxidation which has taken place. Thelevels of the blue spots on the TLC plate indicate the relativeremaining of un-oxidized or un-neutralized glutaraldehyde. The resultsindicated equal volumes of bleach (5% NaOCl) can effective neutralize2.4% glutaraldehyde in 20 minutes. TABLE 3 Effect of Bleach (5% NaOCl)and Glutaraldehyde (2.4%) Mixing Ratio Exp. # 6-1 6-2 6-3 6-4 6-5 6-6 R5% NaOCl (μL) 100 200 350 500 650 800 Ref. 2.4% Glut. (μL) 900 800 650500 350 200 Glutalde- NaOCl:Glut. 0.31:1 0.70:1 1.51:1 2.8:1 5.2:111.2:1 hyde Mole Ratio TLC Most Some Little No Visualization glutaralde-glutaralde- glutaralde- glutaraldehyde hyde left hyde left hyde leftleft

Example 7

[0050] The same experiment in Example 6 was repeated with the aid ofadditional base. The added base slightly promotes the glutaraldehydeoxidation (from the darker colors in Vials 6-2, 6-3 and 6-4 solutionsand a little lighter colors of the corresponding blue TLC spots). TABLE4 Same as Table 3 with Additional Base (20 minutes reaction time) Exp. #6-1 6-2 6-3 6-4 6-5 6-6 R 5% NaOCl (μL) 100 200 350 500 650 800 Ref. 1NNaOH (μL)  10  10  10  10  10  10 Glut 2.4% Glut (μL) 900 800 650 500350 200 NaOCl:NaOH:Glut 0.31:0.046:1 0.70:0.052:1 1.51:0.064:12.802:0.083:1 5.20:0.12:1 11.2:0.21:1 Mole Ratio TLC Most Some Little Novisualization glutaralde- glutaralde- glutaralde- glutaraldehyde hydeleft hyde left hyde left left

Example 8

[0051] The same experiment in Example 7 was repeated with longerreaction time (6 hours instead of 20 minutes). It was found that nofurther oxidation occurred beyond the levels in that of Example 7. Thisis an important finding that it supports that the oxidation ofglutaraldehyde is fast. Although the reaction time is important duringthe first 20 minutes, it appears no longer important after that. On theother hand, the amount of the oxidants, such as bleach or hydrogenperoxide, is crucial. TABLE 5 Same as Table 4 with Extended Time (6hours instead of 20 minutes) Exp. # 6-1 6-2 6-3 6-4 6-5 6-6 R 5% NaOCl(μL) 100 200 350 500 650 800 Ref. 1N NaOH (μL)  10  10  10  10  10  10Glutaralde- 2.4% Glut (μL) 900 800 650 500 350 200 hyde NaOCl:NaOH:Glut0.31:0.046:1 0.70:0.052:1 1.51:0.064:1 2.802:0.083:1 5.20:0.12:111.2:0.21:1 Mole Ratio TLC Most Some Little No Visualization glutaralde-glutaralde- glutaralde- glutaraldehyde hyde left hyde left hyde leftleft

[0052] (B) Neutralization of OPA (Examples 9-13)

Example 9

[0053] In 6 vials (2 mL) indicated below as 9-1 through 9-6, 100, 200,350 500, 650 and 800 μL of hydrogen peroxide (10% hydrogen peroxide) wasadded respectively, OPA (0.55%) of different volumes, 900, 800, 650,500, 350 and 200 μL were added to beakers 9-1 through 9-6, respectively(Table 6). The solutions were shaken briefly and allowed to stand for 20minutes. The solutions were spotted onto TLC silica plate on plastic(Aldrich) and was blown with air for 1 minute before developing in anethanol:methylene chloride (5:95(V/V)) solution. The plates were brieflydipped in Schiff's reagent (Fluka) (diluted to 10% with ethanol) andheated in an oven (75° C.) for 5 minutes for visualization to determineif any spotting resulted (to see black spots with pink background). Onlythe reference OPA showed a black spot. To further confirm this result,200 μL 1.0% glycine was added into each vial and the color visualized in5 minutes. Only the reference OPA gave a green-black color and all theothers do not show a color. One may question if hydrogen peroxide woulddestroy the Schiff's base and therefore its color. To confirm this, to0.5 mL of the Schiff's base solution (obtained from mixing the reference1.0 mL of 0.55% OPA with 200 μL 1.0% glycine at room temperature for 5minutes), 500 μL 10% hydrogen peroxide was added and mixed. Theresulting color was even darker. Therefore, the above method is valid(Schiff's base was not destroyed by hydrogen peroxide). TABLE 6Oxidation of 0.55% OPA with 10% Hydrogen Peroxide Exp. # 9-1 9-2 9-3 9-49-5 9-6 R 10% H₂O₂ (μL) 100 200 350 500 650 800 Ref. 0.55% OPA (μL) 900800 650 500 350 200 OPA H₂O₂:OPA Mole Ratio 8.0:1 17.9:1 38.6:1 71.7:1133.2:1 286.8:1 TLC Visualization No OPA left (No TLC black spot) OPAColor Visualization No OPA left (No dark-green color of Schiff's base)after Mixing w/1% Glycine

Example 10 Oxidation of 0.55% OPA with 10% Hydrogen Peroxide (LessAmount of Oxidant)

[0054] What is the minimum amount of hydrogen peroxide needed toneutralize per volume of 0.55% OPA? Example 9 was repeated using muchless amount of hydrogen peroxide (Table 7). The same procedure wasfollowed. After addition of glycine, only the Vial 9-6 showed dark greencolor, i.e., there was OPA not neutralized in this vial. OPA in all theother vials were all neutralized. The results indicated that only 2%volume of 10% hydrogen peroxide can be used to effectively neutralize0.55% OPA. The volume of hydrogen peroxide can be reduced with moreconcentrated hydrogen peroxide solution. TABLE 7 Neutralization of 0.55%OPA with 10% Hydrogen Peroxide (With less oxidant) Exp. # 9-1 9-2 9-39-4 9-5 9-6 R 10% H₂O₂ (μL)  100  80  60  40  20  10 Ref. 0.55% OPA (μL)1000 1000 1000 1000 1000 1000 OPA H₂O₂:OPA Mole Ratio 7.171:1 5.737:14.302:1 2.868:1 1.434:1 0.717:1 Color Visualization No OPA left Littleafter Mixing w/1% Glycine (No dark-green color of Schiff's base) OPAleft

Example 11

[0055] The similar experiment as that for Example 6 (except colorvisualization was used instead of TLC visualization) was conducted with5% potassium persulfate as the oxidant (Aldrich 37,982-4, lot 21028BN)and OPA as the aldehyde (Table 8). TABLE 8 Oxidation of 0.55% OPA with5% Potassium Persulfate Exp. # 6-1 6-2 6-3 6-4 6-5 6-6 R 5% K₂S₂O₈ (μL):100 200 350 500 650 800 Ref. 0.55% OPA (μL) 900 800 650 500 350 200 OPAK₂S₂O₈:OPA Mole Ratio 0.501:1 1.128:1 2.430:1 4.512:1 8.380:1 18.049:1Color Visualization Some OPA left Little No OPA after Mixing w/1%Glycine OPA left left

Example 12 Oxidation of 0.55% OPA with Bleach (5% Sodium Hypochlorite)

[0056] The similar experiment as that for Example 6 (except TLC was notused) was conducted with household bleach 5% sodium hypochlorite and OPAas the aldehyde (Table 9). It could be concluded that oxidation wascomplete in all the vials. Based on this data, the bleach amount couldbe further reduced. TABLE 9 Oxidation of 0.55% OPA with Household Bleach(5% sodium hypochlorite) Exp. # 6-1 6-2 6-3 6-4 6-5 6-6 R 5% NaOCl (μL)100 200 350 500 650 800 Ref. 1N NaOH (μL)  10  10  10  10  10  10 OPA0.55% OPA (μL) 900 800 650 500 350 200 NaOCl:NaOH:OPA Mole 1.820:0.271:14.096:0.305:1 8.822:0.375:1 16.383:0.375:1 30.425:0.488:1 65.532:0.697:1Ratio Color Visualization No OPA left after Mixing w/1% Glycine

Example 13 Oxidation of 0.55% OPA with Bleach (5% Sodium Hypochlorite)(Less Amount of Oxidant)

[0057] Example 12 was repeated using much less amount of bleach and theresults are shown in Table 10. The same procedure was followed. Afteraddition of glycinc for 5 minutes, only the Vials 6-5 and 6-6 showed adark green color, i.e., there was OPA not neutralized in these 2 vials.Based on our understanding of OPA/Glycine Schiff's base color behaviors,we know there was only trace amount of OPA un-neutralized in the Vial6-4. Thus, based on Vial 6-3, about 6% volume bleach (5% sodiumhypochlorite) can be used to neutralize of 0.55% OPA. This is a verydesired result considering the inexpensive price of household bleach andthe absence of concern of disposing bleach to the drain. If 10-13%sodium hypochlorite was used, only 3% volume will be needed. TABLE 10Oxidation of OPA (0.55%) with Bleach (5% Sodium Hypochlorite) (With lessoxidant). Exp. # 6-1 6-2 6-3 6-4 6-5 6-6 R 5% NaOCl (μL)  100  80  60 40  20  10 Ref. 0.55% OPA (μL) 1000 1000 1000 1000 1000 1000 OPANaOCl:OPA Mole Ratio 1.638:1 1.311:1 0.983:1 0.655:1 0.328:1 0.164:1Color Visualization No OPA left Little OPA Some OPA left after Mixingw/1% Glycine left

[0058] (C) Fish Tests

Example 14 Fish Tests

[0059] California Code Regs (“CCR”) Title 22-Fathead Minnow HazardousWaste Screen Bioassay.

[0060] The following tests were conducted to determine whether aldehydesneutralized by the oxidant, hydrogen operoxide, was hazardous under theCalifornian regulation except that a more stringent concentration of 750mg/L was used instead of the 500 mg/L concentration of the Californianregulation.

[0061] (a) Hydrogen peroxide (5%) failed fish test (0% survival at 750mg/L concentration in 48 hours).

[0062] (b) OPA (125 mL, 0.55%) and hydrogen peroxide (25 mL, 5.0%) weremixed thoroughly and waited for 20 minutes before fish test. The moleratio of OPA to H₂O₂ is 1 to 7.2. Test results indicated that 2 out ofthe 10 fish died in 48 hours (80% survival) and 4 out of the 10 fishdied in 96 hours (60% survival). Thus, this composition would surpassthe less stringent Californian regulations.

[0063] (c) OPA (250 mL, 0.55%) and hydrogen peroxide (83.3 mL, 3.0%)were mixed thoroughly and waited for 20 minutes before fish test. Themole ratio of OPA to H₂O₂ is 1 to 7.2. The results indicated that allfish survived the challenge (100% survival in 750 mg/L concentrationafter 96 hours) and exceeded the Californian regulations.

[0064] In the preceding detailed description, the invention is describedwith reference to specific embodiments thereof. It will, however, beevident that various modifications and changes may be made theretowithout departing from the broader spirit and scope of the invention asset forth in the claims. The specification and drawings are,accordingly, to be regarded in an illustrative rather than a restrictivesense.

What is claimed is:
 1. A method for making a neutralized aldehyde oflessened toxicity comprising the steps of: a) providing an aldehyde; andb) contacting the aldehyde with an effective amount of an oxidizingagent to render the treated aldehyde as neutralized and less toxiccompared with the untreated aldehyde.
 2. The method of claim 1 whereinthe aldehyde comprises aldehydes selected from the group consisting ofo-phthalaldehyde, glutaraldehyde, formaldehyde and mixtures thereof. 3.The method of claim 1, wherein the oxidizing agent is selected from thegroup consisting of hydrogen peroxide, benzoyl peroxide, peroxyformicacid, peroxyacetic acid, trifluoroperacetic acid, peroxybenzoic acid,ammonium cerium nitrate, nitric acid, ammonium nitrate, potassiumchromate, sodium dichromate, potassium dichromate, chlorine, sodiumchlorate, sodium hypochlorite, potassium hypochlorite, calciumhypochlorite, sodium hypobromite, sodium hypoiodite, potassiumhypoiodite, sodium iodate, periodic acid, sodium periodate, potassiumperiodate, manganese dioxide, potassium manganate, potassiumpermanganate, potassium persulfate, magnesium permanganate, rutheniumtetroxide and mixtures thereof.
 4. The method of claim 3, wherein theoxidizing agent is hydrogen peroxide.
 5. The method of claim 4, whereinthe molar ratio of hydrogen peroxide to glutaraldehyde is at least about1:1.
 6. The method of claim 4, wherein the molar ratio of hydrogenperoxide to o-phthalaldehyde is at least about 0.7:1.
 7. The method ofclaim 3, wherein the oxidizing agent is sodium hypochorite.
 8. Themethod of claim 7, wherein the molar ratio of sodium hypochloride toglutaraldehyde is at least about 1.5:1.
 9. The method of claim 7,wherein the molar ratio of sodium hypochloride to o-phthalaldehyde atleast about 0.6:1.
 10. The method of claim 3, the oxidizing agent ispotassium persulfate.
 11. The method of claim 10 wherein the molar ratioof potassium persulfate to o-phthalaldehyde at least about 8:1.
 12. Themethod of claim 1 further comprising diluting the treated aldehyde witha solution comprises water.
 13. The method of claims 1 to 12, whereinthe treated aldehyde has a LC₅₀ greater than 500 mg/L.
 14. A system forneutralizing aldehydes and making the aldehydes less toxic comprising:a) a container; b) a source of aldehyde selected from the groupconsisting of o-phthalaldehyde, glutaraldehyde, formaldehyde andmixtures thereof directed to the container; and c) a source of oxidizingagent directed to the container to yield treated aldehydes of lowertoxicity than the untreated aldehydes.
 15. The system of claim 14,wherein the oxidizing agent is selected from the group consisting ofhydrogen peroxide, benzoyl peroxide, peroxyformic acid, peroxyaceticacid, trifluoroperacetic acid, peroxybenzoic acid, ammonium ceriumnitrate, nitric acid, ammonium nitrate, potassium chromate, sodiumdichromate, potassium dichromate, chlorine, sodium chlorate, sodiumhypochlorite, potassium hypochlorite, calcium hypochlorite, sodiumhypobromite, sodium hypoiodite, potassium hypoiodite, sodium iodate,periodic acid, sodium periodate, potassium periodate, manganese dioxide,potassium manganate, potassium permanganate, potassium persulfate,magnesium permanganate, ruthenium tetroxide and mixtures thereof. 16.The system of claim 14, wherein the oxidizing agent is hydrogenperoxide.
 17. The system of claim 14, wherein the oxidizing agent ispotassium persulfate.
 18. The system of claim 14, wherein the oxidizingagent is sodium hypochlorite.
 19. The system of claim 14 furthercomprises a source of diluent.
 20. The system of claims 14 to 19,wherein the sources added to the container are controlled to achieve thetreated aldehydes having a toxicity level of LC₅₀ greater than 500 mg/L.